The prior art sectional rail systems for construction a base for plate or board covering often find application in non-bearing or bearing walls. These walls may serve as partitionings and are therefore often provided with doors for access between the rooms concerned. The plate covering frequently consists of plaster boards, as this type of plate has a fire-inhibiting effect and which is economically attractive at the same time. The plaster boards are coated with a cardboard layer contributing to distribution of surface tensions such that the porous plaster board can be handled on the construction site and be screwn onto the underlying construction without breaking.
The sectional rail system consists largely of two kinds of sections—an outer rail and an intermediate rail. The outer rails are often with U-shaped cross-section and the cross-section of the intermediate rails is C-shaped. The cross-sections of both outer and intermediate rails include a sectional back and perpendicularly thereto there is typically two screw webs that lie approximately in parallel opposite each other, forming the base on which the plate covering is laid on and fastened to by screws. At the intermediate rails, the screw webs are reinforced by each their reinforcing web facing approximately perpendicularly inwards in relation to the screw web, whereby the C-shape is approximated.
By mounting, the outer rails are typically fastened in parallel at opposing external limits, most often at ceiling and floor, and with the opening of the outer rails facing against each other. By internal walls, an outer rail is therefore frequently used along the floor and correspondingly along the ceiling. The C-shaped intermediate rails may then be placed in the outer rails, after which the rail assembly is made. By the prior art techniques, this mounting work can be performed in the following ways with associated disadvantages:
By the technique used the most, the distance between the intermediate rails is set out by marking on each of the two mounted outer rails. Then the intermediate rails are pushed into the outer rails, after which they are fixed by fixing tongs that cut a collared hole through both sections. After that, possible insulation in the form of batts with a size corresponding to modular dimensions is mounted between the intermediate rails, and the plaster boards are screwed on the intermediate and outer rails. There are the following disadvantages by this prior art:                The modular dimensions between the intermediate rails may easily deviate, whereby the plaster board cannot be screwed on the intermediate rails with the required exact dimensions from screws to plate edge.        The fixing by the fixing tongs frequently cannot stand when the workmen press the insulation into position.        When screwing the plaster boards on, it is often difficult for a self-tapping screw to get hold of the screw webs at the end parts of the intermediate rails. This is due to the fact that the aforementioned fixing cannot secure the screw web of the intermediate rail to the required extent. Hereby, the screw is just pushing the end part of the screw web of the intermediate rails inwards, and the self-tapping screw can not be fastened at the lower edge of the plate covering thereby, why the plate covering remains loose in this area. Particularly around doors where dynamic action on the plate covering may occur regularly, this can result in that the plate covering of the wall works loose, thereby putting greater demands on maintenance. This depreciation of quality is unwanted in modern building construction.        The rail assembly is time-consuming as, for example, 8.88 rail joints have to be made per meter of wall when the intermediate rail spacing is 450 mm. The construction worker has to carry the fixing tongs with him by each rail assembly and has to provide possibility of an efficient working position, implying a not insignificant work environment challenge as the rail assembly work has to take place partly close to a ceiling far above the height of a man and partly close to the floor.        
Another prior art is found in U.S. Pat. No. 3,680,271. Here, punchings are made in the outer rails and the intermediate rails exactly corresponding to each other such that they may be clicked together. Thereby it is possible to click the intermediate rails securely into position without measuring.                Since the intermediate rails are to be displaced perpendicularly into both outer rails, it is necessary to assemble the entire sectional rail system at a place with ample space around for subsequently erecting the sectional rail system (the wall) in one piece and securing it at the place of building-in.        Moreover, there is therefore to be made intermediate rails that fit the given ceiling height since shortening at the mounting site cannot be effected as the possibility of rail assembly by clicking together is rendered impossible if the intermediate rails are shortened.        The system is not flexible as intermediate rails have to be made for any ceiling height that may occur in a given building project, requiring substantial resources for planning the sectional rail system.        The lateral flanges on the intermediate rails are not kept firmly in against the lateral flanges on the bottom and top rails. The intermediate rails may thus be pressed out of their click-lock when screwing into the lateral flange on the intermediate rails. The intermediate rails may hereby be displaced and the screw may have difficulty in getting hold, to the detriment of the quality of the work performed.        
A third prior art is known from U.S. Pat. No. 3,720,995. Here, stop pins are provided on the outer rails, and corresponding lock pins at the inner side of the profiled back. Thus the work with marking the position of the intermediate rails is avoided. Moreover, the fitting work is facilitated as no hand tools have to be used by the fastening of the intermediate rails. The drawbacks of this prior art is:                There is required a very exact shortening of the intermediate rails as even small deviations of the length of the intermediate rails can entail that some of the intermediate rails will slide out of the locking pins. The cutting tools used by the workmen for shortening frequently do not have the required precision.        In practice, it will imply requirements to factory made intermediate rails and putting the outer rails on chocks, implying great demands on both construction site logistics, planning and mounting work.        The lateral flanges on the intermediate rails are not kept firmly in towards the lateral flanges on the bottom and top rails at the rail joint. The intermediate rails may hereby be displaced and the screws may have difficulty in getting hold, to the detriment of quality.        
Concerning establishing door and window apertures, this work is tedious by all prior art sectional rail systems, why it is left to the building worker's creativity to provide the wanted door and window apertures. Thus, by the prior art for establishing a door aperture it often occurs that one of the intermediate rails are moved half an intermediate rail width, such that a door aperture can assume a standard width of e.g. 900 mm, 1000 mm or 1100 mm. Vertically over the door, two intermediate rails are mounted juxtaposed in order to compensate for the displaced intermediate rail. This is only manifested if the position of the door fits into a modular system of 450 mm. If it is not positioned according to a modular system, two extra intermediate rails have to be used. A unnecessary use of material is thereby produced at the establishing of a door and window apertures in the prior art systems.
Between the two vertical intermediate rails at the door or window aperture, a horizontal lintel is mounted. This is frequently made on the spot of a piece of outer rail which is worked with sheet metal scissors in order to be assembled with the intermediate rails. This is a cumbersome and time-consuming work that reduces the efficiency in the building process.
The mentioned switching around of the intermediate rails at the door and window apertures entail that the advantages of the modular disposition of the intermediate rails cannot be utilised around the door and window apertures. Insulation batts, which have standard dimensions, thus have to be adapted by cutting in all fields around the door and window apertures, which is a relatively time-consuming process.
In addition, in modern construction there are great demands to the quality and productivity in performing the work. Research shows that there is a special need for innovation within the building sector. Here, there is pointed to new thinking for building processes and projecting whereby a greater productivity can be created within the sector. The present invention fulfils the desire for optimisation of the building process by the often used sectional systems for plate covering to the benefit of the productivity in the building sector.